At the top of the list is MS12-034, a combined security update for Microsoft Office, Windows, .NET Framework, and Silverlight. It's an update that addresses vulnerabilities first brought to light by the Duqu malware that surfaced in 2011. Microsoft first patched for Duqu in December 2011. With today's update, Microsoft is addressing multiple "Sons of Duqu" vulnerabilities by patching copies of the code that were found elsewhere in the Microsoft code base.

"This is by far one of the largest security bulletins Microsoft has ever released," said Jason Miller, manager of research and development for VMware, in an email statement to eSecurity Planet.